adsorption - American Chemical Society

(83) Stephens, E. J., and Morris, G. A., Chem. Eng. Progress ..... Anomalies of the temperature dependence of a, or discontinuous ..... rend., 232, 11...
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INDUSTRIAL AND ENGINEERING CHEMISTRY

(53) Leibush, A. G., and Shneerson, A . L., J . Applied Chem. ( U S S R ) , 23,149 (1950). (54) Lerner, B. J., and Grove, C. S., IND. ENG.CHEM.,42,218 (1950). (55) Lin, C. S., Denton, E. B., Gaskill, H. S., and Putnam, G. L., Zbid., 43,2136 (1951). (66) Lyons, M. S., and Thomas, J. V., J . Am. Chem. SOC.,73, 4506 (1951). (57) Lyudkovskaya, M. A.,and Leibush, A. G., Zhzbr. Priklad Khim., 22,558 (1949). (58) McAdams, W. H.,Pohlena, J. B., and St. John, R. C., Chem. Eng. Progress, 45, 241 (1949). I Maier, C. G., J . Chem. Phys., 7, 854 (1939); U.S.Bur.Mines Bull. 431 (1940). Martin, J. J., McCabe, W. L., and Monrad, C. C., Chem. Eng. Progress, 47,91 (1951). Matsuyama, T., Chem. Eng. ( J a p a n ) , 14, 245 (1950). Mickley, H.S., Chem. Eng. Progress, 45, 739 (1949). Miaushina, T., and Kotoo, T., Chem. Eng. ( J a p a n ) , 13, 75 (1949). Nieuwenburg, C. J. van, and Hegge, L. A., Anal. Chim. Acta, 5 , 68-70 (1951). North, E. D., and White, R. R., IND.ENG.CHEM.,43, 2390 (1951). Ogawa, S., Chem. Eng. (Japan),.S-IO, 18 (1945-46). Olson, R. L., and Walton, J. S., IND. ENG.CHEM.,43,703 (1951). Otake, T., Chem. Eng. ( J a p a n ) , 14, 47 (1950). Otake, T., and Takekoshi, H., Ibid., 13, 135 (1949). Pattle, R. E., Tram. Inst. Chem. Engrs. (London), 28, 27 (1950). Pearson, D. A., Lundberg, L. A., West, F. B., and McCarthy, J. L., Chem. Eng. Progress, 47, 257 (1951). Pigford, R. L., and Pyle, C., IND.ENG. CHEM.,43, 1649-62 (19511. PiAsent,. B. R. W., and Roughton, F. J. W., Trans. Faraday Soc., 47,263 (1951). Reed, R. M., and Updegraff. N. C., Im. ENG.CHEM.,42, 226977 (1950). Richardson, E. G., Preprint of Papers Sec. I, p. 23,Joint Meeting

Vol. 44, No. 1

of Am. Soc. Mech. Engrs. and Brit. Inst. Mech. Engrs., London (September 1951.) (76) Sands, A. E., and Schmidt, L. D., IND. ENG.CHEM.,42,2277-87 (1950). (77) Sato, T., Chem. Eng. (Japan), 14, 219 (1950). and Schult, H., Ann. Physik, 7, 103 (1950). (78) Renftleben, H., (79) Sherwood, T. K.,and Woertz, B. B., IND.ENG.CHEM.,31, 1034 (1939). (80)Shneerson, A. L., and Leibush, A. G., J . Applied Chem. (U.S.S.R.),22,553-7 (1949). (81) Sjenitzer, F.,Preprint of Papers Sec. I, p. 18,Joint Meeting of Am. Soc. Mech. Engrs. and Brit. Iast. Mech. Engrs., London (SeDtember 1951). (82) Snyder, R.W.: Z b k , Sec. 11, American Papers (83) Stephens, E. J., and Morris, G. A., Chem. Eng. Progress, 47, 232 (1951). (84) Strauss, H.J., J . Chem. Education, 27, 517-19 (1950). (85) Taylor, G.I., Preprint of Papers Sec. 11, p. 19, Joint Meeting of Am. SOC. Mech. Engrs. and Brit. Inst. Mech. Engrs., London (September 1951). (88) Taylor, G . I., Proc. R o y . SOC.,A, 135, 689 (1932). (87) Turkhan, E. Y.,Zhur. Priklad. Khim., 23, 225-9 (1950). (88) Von Karman, Th., Trans. Am. SOC.Mech. Engrs., 61,705 (1939). J. A m . Chem. Soc., 73, 510 (1951). (89) Wang, J. H., (90)Ibid., p. 4181. (91) Washburn, E. R., and Dunning, H. N., Ibid., 73, 1311 (1951). (92) Weller, S., and Steiner, W. A., Chem. Eng. Progress, 46, 585 (1950). (93) White, G.E.,Trans. A m . Inst. CFem. Engrs., 36, 359-69 (1940). (94) Whitney, R. P., and Vivian, J. E., C h a . Eng. Progresu, 45, 823 (1951). (95) Wilke, C. R., Ibid., 45, 218 (1949). (96) Yoshida, F.,and Tanaka, T., Chem. Eng. ( J a p a n ) , 14, 133, 143 (1950). (97) Yoshida, F., and Tanaka, T., IND.ENG. CHEM., 43, 1467 (1951). RECEIVED November

16, 1951.

T HOPKINS UNIVERSITY, BALTIMORE 18, MD.

Industrial applications of adsorption are widespread enough that this field has ceased to be a specialty in unit operations and is now taking its rightful place alongside other, older fields. This is attested to by the size and number of types of applications on both large scale and laboratory scale, Several large solvent recovery plants utilizing activated carbon started operations in 1951. These efficient automatic plants recover solvents for many industrial processes and are particularly valuable during shortage periods like the present. M o r e work has been reported this past year than in any previous year and the trend seems likely to continue. Subfields, such as chemisorption and chromatography, have developed to the point that a single article cannot d o justice to the entire field.

YPERSORPTION, the industrial process of removing adsorbable hydrocarbon vapors in refining and natural gas operations, has now come of age. The method generally utilizes a moving bed of activated carbon to remove and fractionate the components of a gas stream. Patents which cover various types of apparatus, including those fractionating up to four products and utilizing reflux of the moving carbon stream have been recently issued to Berg and coworkers (80-24). A somewhat similar system was developed by Small (290). A review which included some of the commercial developments recently was published by O’Connor (93.4). Following closely upon this development, a chromatographic scheme for industrial separation of aromatics has lately been introduced (@, 948). The Arosorb process has been announced by Sun Oil Co. for separation of aromatics and a large scale unit is planned for the Marcus Hook refkery. The operation of the sys-

tem follows closely the scheme developed by Rossini in the analysie of petroleum. A stream contammg aromatice ie passed through silica gel until saturation is obtained and then desorption commences. The first of two desorbents washes the bed free of holdup and the second follows to desorb the aromatic compound. The cycle is then repeated, Other applications of adsorption processes to practical designs have been brought to light. The utilization of adsorption of moisture and carbon dioxide for purification of the atmosphere of a submarine has recently been revealed (60). This method uses high pressure to achieve results a t normal temperatures, using sea water to remove heat of adsorption. The method is applicable to other temperatures using Freon or liquid oxygen. Another simple device was developed to remove odors from air-circulating systems (287). The determination of atmospheric contaminants by adsorptive means was presented by Turk and Sleik (318). The practical aspects of drying air in h e d beds were discussed by Eagleton and Bliss (741, who evaluated for various sorbents equations of the usual two-film mass transfer mechanism. The several variables involved in the dynamic adsorption of water vapor on silica gel Piere discussed and evaluated by ROSB and Me-

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INDUSTRIAL AND ENGINEERING CHEMISTRY

Laughlin (269). The mathematics of sorption in beds waa further extended by Amundson (2). Gunthard and coworkers (110) die cussed the linear differential equations of adsorption and of adsorption with reaction, and gave solutions for several caaes. A continuous method of separating gases by a finely divided adsorbent suspended in the gas stream was developed by Robinson (166). I n this method h e particles of adsorbent are used. The process has been applied to the separation of nitrogen from natural gas. Data on adsorption of mixtures of gases are as yet quite sparse, but several studies have recently appeared in addition td that of Lewis (296). These include adsorption of hydrogen and carbon monoxide on Fischer-Tropsch catalysts (99) and various other systems (104, 231,$19,319). One theoretical paper treated this type of system (134). Dynamic adsorption data on various systems were studied by several investigators. Separation factors of 50 to 100 were realized by Hartick and Melkonian for the isotopes of hydrogen at low temperatures and when utilizing thin layers of silica gel a t low pressure with slow removal of the hydrogen. This effect, stated as being counter to classical theory, they labeled the “tunnel effect.” The adsorption wave characteristics of ammonia, butane, cyanogen chloride, and water vapor by charcoal is described by Davis et al. (69). The stripping of carbon disulfide from air by charcoal was evaluated by Vreedenberg by analogy with temperature distribution in a solid in a furnace heated by hot gas. Nomograms are given for evaluation of the constants involved in the mathematical relation. SURFACE AREA STUDIES

A t the recent AMERICAN CHEMICAL SOCIETY meeting in New York City, the question was informally p u t to the assembled members of the Division of Colloid Chemistry as to whether the Brunauer-Emmett-Teller (B.E.T.) theory was acceptable in so far as determination of surface areas is concerned. There was no dissent from this; it was stated by several proponents of the “liquid slab” model that for the order of one to two molecular layers, the B.E.T. theory was a rather good theory from several points of view. Data from the field seems to indicate the usefulness of the B.E.T. and of the Harkins-Jura (H-J) equations for surface area determination. Agreement between these two methods wm found for heptane vapor on a large number of solids if the area assigned to the molecule was 64 square A. and the k constant of the H-J equation was 16.9 or 18.2(199). These values were for a c value of the B.E.T. equation between 19 and 174,in agreement with previous calculations that, fos values of c between 25 and 250, good agreement would be postulated for these two mechanisms. Adsorption of krypton or nitrogen on organic solids was measured by Zettlemoyer (344),who concluded that the B.E.T. theory provides a satisfactory method for investigating surface areas of such materials with nonpolar gases. Corrin (69) concluded from a study of several adsorbates on various solids that the B.E.T. equation gives more self-consistent results and a larger number of straight-line plots than does the Huttig equation, although the data from the latter become more self-consistent the larger the surface area of the solid. As this occurs, agreement between the areas calculated by the two equations improves. Adsorption by krypton a t temperatures below that of boiling nitrogen has been utilized by Harris and Wolock (120,121) to reduce the apparatus error in the determination of surface areas of very small value and the B.E.T. equation was found to apply to such preas of organic films that have very low roughness factors. Innes has devised a procedure for rapid surface area measurement utilizing a dynamic flow system and finding good agreement with the B.E.T. (161). Other investigators have presented work involving area measurement utilizing still other vapors. Lauterbach, Laskin, and

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Leach (101) measured the surface area of uranium dusts using ethane. Russell and Cochran (971)used nitrogen, butane, and propane, as well aa stearic acid, on alumina powders. They found that the B.E.T. equation did not fit the data, but that fair agreement of surface areas could be obtained if arbitrary straight lines were drawn utilizing portions of the data. Adsorption of stearic acid gave consistent results on nonporous samples. Smith, Pierce, and Cordes (296) measured surface areas by the “Point B” method with cyclohexane and benzene on graphitized carbon black and found good agreement if the areas assigned to the molecules of adsorbate were calculated on the assumption that the molecules lie flat on the surface. Various methods of estimating the surface area of adsorbenta have been proposed. Hirst and Lancaster (138)compared methods utilizing a solution of stearic acid in benzene, varying the concentration while holding the temperature, and hence the saturation concentration, constant, and varying the temperature (and saturation concentration), keeping the relative concentration constant. They obtained good agreement for the two methods on various solids and stated that the temperature-dependence method involved less manipulation and smaller experimental errors. The surface area of zinc oxide was estimated from the lattice constants and the chemisorption of water vapor by Miyahara (919)and was shown to agree with the area measured by benzene adsorption. F’u and Bartell (99)have proposed a procedure for estimation of surface area from low temperature isotherms without the assumption of molecular size for the adsorbate. The data are plotted according to the Gibbs equation and the point corresponding to capillary condensation is identified. The area is evaluated by use of the surface tension of the adsorbate. Jura and Powell (163)have suggested that, if there is a significant change in the rate of adsorption a t the completion of a monolayer, evaluation of the kinetics will yield the surface area. Values so obtained differed from those calculated from equilibrium data by at most 20%. Halsey (116)derived an isotherm equation for COoperative multilayer adsorption from the London law for the diepersion force, assuming an exponential distribution of adsorbing centers. When conditions are such that saturation of the fist adsorbate layer is complete at a low value of the relative pressure, the equation yields data that give a good B.E.T. plot with a satisfactory value of the volume required to form a monolayer. Surface area measurements have been utilized for studies of metal systems (194,969-961), clays (IO@, and alumina hydratee (979). Dean proposed the adoption of a unit of adsorption-the gibbs-defined as 10-10 moles per square centimeter (61). CHROMATOGRAPHY

The number of articles on chromatography increased greatly during the past year. In addition the application of ion exchange systems has attracted a good deal of interest and, as this field R i more properly a subdivision of the ion exchange operation, no attempt will be made here to evaluate it. Theories of chromatography have been advanced treating of the mathematics of the sorption under a variety of conditions. TunitskiK and Cherneva (317)have developed equations for either adsorption or diffusion as the rate-determining step. YanovskiI (840) calculated the maxima of desorption curves from the distribution functions of heats of adsorption over the surface for nonhomogeneous surfaces. Rosen and Wmsche (268)introduced the admittance concept into the kinetics of chromatography for a variety of assumed rate-controlling mechanisms. For a case of nonlinear kinetics, they present representative results obtained with an electronic analog computer. Rose, Lombardo, and Williams (266)have utilized an IBM digital computer for the calculation of a selective adsorption column. Smit (292) extended the work of Wilson and of DeVault, deriving the conservation equation for a single solute and introducing a correction for the volume of the adsorbed phase. Schute (282)has rebutted the

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Vol. 44, No. 1

tures of hydrocarbons by Spengler and Krenkler (296), steroids (182), indicators (193), and dyes (58, 258, 279, 300) by various authors. The development, refinement, and improvization of chromatographic apparatus and methods have been especially prolific. The Tiselius-Claesson interferometric adsorption analysis appara, t u s was modified in design to increase its versatility and to simplify ease of manipulation (140). The Mitchell-Haskins Chromatopile, a simple column of filter paper disks, has been marketed (118). Zechmeister has modified this device to allow the use of an enclosed system (343’) .4 titrimetric gas analyzer ie reported by Turkeltaub (519) somewhat similar to the gaseous system previously marketed by Burrell. A continuous stripper was developed by Hopkins (141) for use with adsorbent elutant streams. Numerous devices have been presented for automatic fraction collection on columns (72, 101, 107, 122). New types of apparatus include a cell distribution train (54), a column formed of rigidly supported demountable glass cylinders of different lengths (98), and a “chromatobar,” which is a rigid column of adsorbent in a matrix of gypsum (614). This last has some of the adC O U R T E S V C A R B I D E AND C A R B O N C H E M I O A L S C O . vantages of the chromatopile. In addition, it can Equipment Using Activated Carbon for Recovery of Acetone Vaporized in be examined by radiaticn which is absorbed by Manufacture of Cellulose Acetate Rayon glass; it is applicable t o ascending development; L e k End view of sdrorbers end steam inlet valves extrusion is unnecessary before use of a streak Right. Centralized control inrtrument panel reagent; and the streak can be scraped off before further work. objections of Craig to the view that partition chromatography deApparatue for paper chromatography apparatus has been furpends on liquid-liquid partition by postulating that the stationary ther augmented by the “chromatopack” (254), a pack of paper liquid phase, bound to the carrier, does not have the same propstrips which may be handled as a single strip, and by various other innovations (93, 167, 827, 189). erties as in the free state. Trueblood and Malmberg (914) have shown that a t low concentrations, numerous isotherms are linear Fluorescent techniques have been aided by the use of fluorescent adsorbents (W), and by an apparatus consisting of a paper and thus can be evaluated by simple chromatographic theory. between an ultraviolet transparent sheet and a fluorescent Other theoretical treatments were presented by Billen (288) and screen (97). High temperatures, as well as temperature control, by Glueckauf (104). Mechanism of separation of inorganic systems was discussed by have been suggested by Counsel1 et al. as presenting advantages for improving separation of highly concentrated and viscous maseveral papers (264, 274, 285, 304). The relative rates of formaterials (63). tion of insoluble hydrous metal oxides, ionic exchange, orientation Numerous reviews of the field of chromatography have apof coordinated water groups, and electrostatic forces are postupeared in various languages (44, 64, 85, 118, 127, 192, 200, 229, lated as contributing. The Jones reductor was proposed as a 238,266,278,293,331,3%). model for the kinetics of chromatography (177). A rapid method for determining adsorption capacity waa demonstrated by Gapon and Zhupakhina (95). LIQUID PHASE ADSORPTION Specificity of adsorbent and of adsorbate was the subject of Isotherms of adsorption from solutions by porous solid in the several articles. LeRosen and coworkers (194) mathematically neighborhood of the critical mixing temperature presented by considered donor-acceptor and hydrogen bond interactions as well Krasil’nikov and Kiselev (179)indicate that well below that temas the carbon side-chain, with solvents assigned arbitrary values perature the form of the isotherm is Sshaped. Above this temas competitive agents. Stewart (297) presented data shoaring perature, in the region of unlimited mixing, the adsorption exthat the extent of water deactivation of activated alumina and hibits a maximum. At intermediate temperatures the isotherms magwsium carbonate controlled the separation of substituted have intermediate shape. On nonporous solids somewhat reanthraquinone compounds. Smith and LeRosen (294) showed verse behavior was observed but the system chosen for this study that ketones were adsorbed due to interactions between their was a different one than for the first (176). carbonyl oxygen and the adsorbent. Brockmann (31)studied the Constable has shown from thermodynamic considerations that adsorption affinity of various systems of adsorbates and has the Freundich isotherm results from assumption of linear variashown that for dyes the acidity or alkalinity of the adsorbent is tion of the free surface energy with composition in the controlling. For compounds of the type RNHCOR’, neither the surface layer (61). It has been previously shown for gaseous adsorbent nor the solvent controls, but rather the complexity of systems that a similar result occurs from the assumption of a the adsorbate. linear distribution of energy of binding over the surface. Both Data have been presented for separation of amino acids (19,27, Hill (132) and Ono (289)have investigated the statistical thermo48, .%‘/is, 244), fatty acids (47, 144), sugars (646,314, S34), phenol dynamics of liquid phase adsorption. Brown (36) applied the and cresylic acids (863, 8&), and for the resolution of nitrocelluHarkins-Jura equation to the data previously reported by Hanlose of varying molecular weight (84). Applications to photograsen, Fu, and Bartell and compared results with those obtained phy have been discussed by James and Vanselow (152). Inorby the B.E.T. equation. Glueckauf (103) showed that for adganic ions were studied by various authors (117, 249, SOS), mix-

January 1952

INDUSTRIAL AND ENGINEERING CHEMISTRY

sorption of organic acids from aqueous solutions by charcoal the solid acts as an anion exchanger. It is postulated that if the Ha0 + is adsorbed according to the Langmuir equation, identical results would be obtained as if molecular adsorption followed an exponential isotherm, Kipling and Tester suggest on theoretical grounds that the mathematical forms of both the Freundlich and the Langmuir equations render them inapplicable to liquid-phase results (176). Miller et al. discussed the applicability of Freundlich isotherms to various cases of adsorption of solute and solvent as applied to clay and bauxite. They postulated the adsorption of solvent by adsorbed solute molecules to explain some of the data. Zechmeister suggested that the adsorption affinity depends not so much on the presence or absence of certain functional groups as it does on the over-all shape of the adsorbate molecule (342). Competitive adsorption from aqueous solution between hydrophobic and hydrophilic molecules and ions was discussed by Merker and Zisman for water-soluble amines (all). Eagle and Scott have presented design data for liquid phase adsorption processes, utilizing the toluene-iso-octane system (73). Long-range forces in solution, postulated and disproved succeasively by biochemical studies in the past, have been suggested by Carroll (43)to explain the behavior of serum albumin. When the albumin molecule adsorbs fewer than 100 dye anions, it was easily attacked by pepsin, but a t greater than 200 anions it was not attacked by 0.1% pepsin. Erbacher ( 7 9 ) stated that in the case of ion adsorption on metal surfaces, the Freundlich isotherm cannot be interpreted as the summation of Langmuir isotherms belonging to different active centers, but is conditioned by the electrostatic interaction of the adsorbed ions. F r u m k i (91) evaluated the dependence of the charge density on the equilibrium potential and the concentration of the ions and derived the previously reported equations of Gapon and of Lange and Berger, utilizing the theory of the double layer of Stern. The adsorption of ions of various types on several solids were reported: copper and zinc on calcium carbonate (40),bivalent metals on trivalent metal hydroxides (%as), various ions on alumina (89, 108, 286), and miscellaneous systems (180, 2660, 291). The catalytic behavior of adsorbed ions on aqueous reactions was reported by Uzumasa and Okura (320). Liquid phase adsorption of ( C U ( N H ~ ) ~ )or + +methylene blue was used,as a tool to study the aging of precipitates (321). A large number of specific systems of liquid phase adsorptions were reported. These included essential oils by charcod (170), dyes on clays (316)and on silica gel (lla),sugar on quartz (77), boric acid on charcoal (160), proteins on clays (a&?), benzene and methanol on charcoal (270), and long-chain surface active agents on evaporated metal films (339), as well as the various studies listed above. Specific adsorption of ions was studied by Booth (28)as a tool in crystallization work. Numerous liquid-liquid interface adsorption systems were reported. These involved surface active agents by conventional techniques (306,33.3) and radiotracer technique (166)at liquidair interfaces, high molecular weight paraffins naturally occurring in oil-water interfaces (66),surface active agents at organic solvent-water interfaces (@), vapors a t a liquid-air interface in the case of helium (14.9)or hexane (241)on water, and the behavior of stearic acid monolayers on water in contact with saturated organic vapors (63). Hutchinson (146) discussed the convention of locating the plane of the interface with respect to which calculations of the surface concentrations of materials adsorbed there are made. Aids to the study of liquid phase adsorption were advanced by several authors. Chief of these was the radiotracer methods coming into wider use (166,167,190,276,280). The polarograph was used by Suzutani (301)and a surface balance waa modified by Dean and Hayes (63)for the measurement of the effect of vapors on monolayers. This last was claimed% be accurate to 0.05 dyne and 0.1 X 10-10mole per square cm.

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PREPARATION AND PROPERTIES OF VARIOUS ADSORBENTS

Ashley and Innes (8)investigated the control of the physical structure of a silica-alumina gel, finding that the porosity may be increased by increasing the time and temperature of aging of the gel, using a higher silica content in the range from 3 to 7%, using a higher p H of aging of the silica in the range 3 to 7.5, adding silicate and acid to a gel already formed, and greatly decreasing drying time. They postulate that all but the last variation increase the rigidity of the gel so as to render it more shrinkage-resistant, whereas the last variation does not permit the time required for rearrangement of the gel necessary to shrinkage. The activity of the gel for proton-donor catalysis can be increased, according to Ohta (256), by shortening the period of contact of the undried gel with electrolytes and by drying below 500" C. Gyani has shown (111)that evacuation of a gel above a given temperature during ita' preparation yields increased adsorption; aging of a gel increases adsorption at high pressures arid decreases it at low temperatures; hysteresis occurs if evacuation above 300" C. is used in the preparation; and aging also affects the hysteresis. Preparations of various types of gels have been variously repbrted. Water-rqellent aerogels have been reported by the National Research Council of Canada (46).Methods of producing spherical gel particles were patented by Ashley ( 7 ) , Elam (76), and Kimberlin (l72),and various gels preparations were reported by a number of authors (14,171, 186,232, 284). Regeneration of gels was studied by severai investigators. The addition of an organic nitrogen base to steam lessened the loss of surface of xerogels upon revivification (4). Murray (2.38)recommends steam regeneration of chromatographic columns. Studies of the loss of surface area upon heat and steam treatment were made by Polack, Segura, and Walden (262). A practical method of cooling reactivated gel beds by evaporation of liquid charged to the bed was advanced by Williamson (337). Selwood (283) reported the magnetic susceptibility of active and inactive gels and concluded that the Weiss constant of the Curie-Weiss law relating temperature to susceptibility is indicative of the activity. Fewer articles dealt with preparation of carbon adsorbents, which is understandable in view of the large amount of accumulated data. Morrell and Tobiasson (224)reported a doubly impregnated charcoal, using an active metal salt and a copper ammonium carbonate complex-silver thiocyanate treatment. Weiss reviewed the modification of active carbons for continuous fractional adsorption (330). Treatment of charcoal with oxidizing agents was studied by Mukherjee and Bhattachatya (226). Cremer (66) has shown that for adsorption according to the Freundlich equation, the exponent of the concentration term is a function of a critical temperature, which in some cases is proportional to the pretreatment temperature. N i l s et al. showed that increased severity of acid activation of bentonite clays resulted in increased surface area, but not necessarily in increased catalytic activity (217). Garcia (96) found from the hydration capacity of montmorillonite that the exchangeable cations are located in the interlaminar spaces. Gonsale5 and Deitl; (106)showed that the maximum surface area which was obtained upon acid activation of bentonites occurred when a11 the adsorbed water was eliminated. As the water of constitution was removed, the surface area decreased slightly. Basal exchange of clay with potassium chloride and activation with acid was reported by Sasaki to produce a highly active adsorbent (276). Numerous papers dealing with preparation of adsorbents for chromatographic work have been reported above. Burma and Banerjee (38)discussed the preparation and standardization of alumina, using dye adsorption for the latter. Treatment of paper with cetyltrimethylammonium bromide results in a net positive charge on the adsorbent, which is useful in chromatographic study of colloidal electrolytes and anionic detergents, according to

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I N D U S T R I A L AND E N G I N E E R I N G CHEMISTRY

Rutter (275). Iida and Ishimoto reported that alumina is increased in activity when heated above 300' C. and the activity is a maximum a t 400' to 600"C., decreasing to zero when treated at 1200' C. The activity decreased with aging a t the higher temperatures and acid-washed alumina is superior to water-washed material (149). Revivification of metallic adsorbents was found better to rest8re the activity when treated with peroxy acids or per acids ($10). The activation of magnesium oxides was studied as a function of temperature and duration of activation by Venture110 and Burdese ( 3 2 2 ) . The surface activity of gibbsite was found to increase sharply with increasing temperature up to 410" C. and then to fall off when heated a t higher temperatures, becoming negligible and the surface area falling to zero a t 1000" C. (109). CHEMISORPTION

Taylor has recently shown (306) that the rate law of the form aebmq, proposed initially by RoginskiI and Zeldovich, where a is initial rate of adsorption and q is the amount or fraction of gas adsorbed, will render satisfactorily, and in most cases over the whole course of the process, a large mass of existing experimental dataof slow adsorption rates of gasesondifferent solids. Anomalies of the temperature dependence of a,or discontinuous changes in a,are ascribed to intrinsic surface heterogeneity. The exponential factor expresses the decrease of the probability of availability of sites with progressing adsorption. The equation was shown to apply to a number of heterogeneously catalyzed reactions which fail to follow any algebraically ordered mass action law over an extended range of the conversion. Dowden discussed the chemisorption on metals in the light of the band theory and Pauling's resonating valence bond theory (67). Trapnell discussed the usefulness of clean wire and evaporated metal surfaces for study of relative chemisorptions and relative reaction rates. Activated adsorption and oxidation of metals were studied by Moore ( $ 2 3 ) . Boudart ( 3 0 ) proposed that the factors associated with the concept of active centers may be related to the electronic chemical potential of the adsorbent. Kummer and Emmett (183) studied the exchange of radioactive and nonradioactive carbon monoxide on iron catalysts and suggested that the behavior could be explained if the surface acts as if i t were partly homogeneous and partly heterogeneous. Similar studies by Eischens indicated that the exchange goes fastest where there is weakest chemisorption, but that oxidation to carbon monoxide is greatest where there is strongest sorption. Other chemisorption studies on metals included various gases on barium getters (368),hydrogen on copper (187, 189), oxygen on tungsten ($9), nitrogen on zirconium and iron (94), various gases on steel and chromium (,%)I), and nitrogen, argon, and oxygen on molybdenum (224). The sorption of strong organic bases from aqueous solution by charcoal was ascribed to the presence of chemisorbed oxygen, rather than water, by Wilson and Bolam (338). They stated that the mechanism of sorption of strong inorganic acids involves physical adsorption on the carbon. Organic compounds sometimes undergo reaction with chemisorbed oxygen on channel blacks, but this factor is not large enough to be of primary significance in use of these carbons in reinforcement ( 2 5 3 ) . The influence of a chemisorbed film on the physical adsorption of krypton by copper oxide was studied by Stone and Tiley (299). Stone proposed ($98) that the semiconductivity of the solid be used to study chemisorption, since the adsorbed atom or molecule in general acts like a lattice defect near the surface. Sundry other studies on oxides were made as follows: water vapor on zinc oxide ($21,999); ammonia on various oxides ($62); carbon monoxide and hydrogen on zinc oxide-chromium oxide mixtures (100);and ion adsorption on alumina (89). Hydrogen on tungsten disulfide was studied by Friz (90) who found that be-

Vol. 44, No. 1

tween 20' and 450' C. the surface adsorbed the gas, and above 200' C. the gas dissolved in the lattice. Somewhat similar results were obtained on ethylene a t 50" to 100' C. lower temperatures. KINETICS O F A D S O R P T I O N

On the assumption that the activation energy for the adsorption process is proportional t o the zero-point energy between a gas and a solid, Halsey derived an expression for the rate of adsorption of a gas on a nonuniform surface and showed that it is in qualitative agreement with the observations of Taylor and Liang for the adsorption of hydrogen on zinc oxide (116). Weber and Laidler (529) showed that the rates of desorption of ammonia on iron catalysts decrease markedly as the surface becomes more fully covered. The results were interpreted in terms of the repulsive forces between the adsorbed molecules. Wiig and Smith (536)reported on the kinetics of desorption of ethyl chloride from activated carbon and stated that the fraction of the gas retained a t a given time was less for highly activated samples, or in other words, that less time was required to remove a given fraction of gas from a highly activated sample than from one with less activation, if all samples were prepared from a given base char. Sorption of organic vapors by thin films of cast cellulose acetate was studied by Mandelkern and Long (2067,who stated that attempts to interpret the sorption by a modification of Fick's law as a diffusion were unsuccessful, even when allowing for a dependence upon vapor concentration. Kinetics of adsorption as a measure of surface area of adsorbents was studied by Jura and Powell (165) and Miyahara ($19). Eagle and Scott (75) demonstrated graphical methods of evaluation of the fractional approach to equilibrium. Adsorption coefficients calculated from kinetic data of dehydration of ethanol differed from those measured for adsorption of ethanol and of water by large factors, indicating that adsorption and catalyzing centers are different on alumina, as reported by Antipina and Frost ( 3 ) . INDUSTRIAL APPLICATIONS

Industrial applications of adsorption are continuing to be made a t a rather high rate. The hypersorption process has been installed a t a large number of locations and many patents on various types of apparatus for this process have been issued, aa discussed above. A vapor sorber for the removal of petroleum vapors as well as water, oil emulsions, and dirt from compressed gases has been announced by Selas Corp. The apparatus combines a ceramic filter and an activated carbon adsorbent. The unit is simple in design and is supplied in standard units of 100 to 500 cubic feet per minute and a t pressures to 150 pounds per square inch, Laboratory work has been carried out on a process to store methane on fuller's earth (106). A pilot plant for this process, termed the Methanite process, has been constructed but commercial applications have not yet been made. By far the largest industrial use of vapor adsorbent activated carbon is for the recovery of low boiling solvents vaporized in many manufacturing operations. Recovery plants installed or in process of being installed as of October 31, 1951, in Worth and South America have a recovery capacity of well over 2 billion pounds of solvents per year. Such plants generally utilize highly adsorptive activated carbon in the form of small, hard, dense pellets which give a low resistance to air passage and resist breakage during use. These modern plants, which are usually automatically operated and controlled, recover solvents with extremely high recovery efficiency at very low cost. They are essential to the economical operation of many industrial processes, such as, for example, the manufacture of cellulose acetate rayon. Such plants are particularly valuable during a national emergency when there is a shortage of solvents. As an example, plants in-

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INDUSTRIAL AND ENGINEERING CHEMISTRY

35

(5) Arii, K..and Tanska, M., J. C h . SOC.Japan, 69, 9 1 4 (1948). ( 6 ) Arkharov, V. I., Somova, E. V., and Chukina, T. P.,Doklady Akad. Nauk S.S.S.R., 76, 209-10 (1951). (7) Ashley, Kenneth D., U. 8.Patent 2,555,282(May 29, 1951). (8) Ashley, K.D., and Innee, W. B., paper presented a t the 120th Meeting of the AMERICAN CHEMICAL SOCIETY, New York. (9) Aston, J. G., paper presented a t the 119th Meeting of the AMERICAN CHEMICAL Socrmm. Boston, Mass. (10) Aston, J. G.,Szasz, G. J.. and Kington, G. L., J . Am. Chem. SOC.,7 3 , 1937-8 (1951). INDIVIDUAL STUDIES O F EQUILIBRIUM DATA (11)Avgul, N. N.,Dzhigit, A. M., Dreving, V. P., Gur'ev, M. V., Kiaelev, A. V., and Likhacheva, 0. A., Doklady Akad. Nauk The large number of references published during the past year S.S.S.R., 77, 77-80 (1951). preclude complete discussion of the individual studies of equi(12) Avgul. N. N.,Dzhigit, 0.M., Isirikyan, A. A., Kisclev, and librium data. For the convenience of persons interested in such Soherbakova, K. D., Ibid., 77, 625-8 (1951). studies, a cromindex reference list follows. (13) Avgul, N. N., Dzhigit, 0. M., Kamakin. N. M., Kiselev, A. V., Luk'yanovich, V. M., Neimark, I. E., and Sheinfain, R. Yu,, Adsorbents of Major Interest. CHARCOAL. (6, 20-24, 41,60, Ibid., 76,855-8 (1951). 59, 70,71,73, 103, 160, 168, 170, 196, 196, 208, 224, 225, 234, (14) Baird, Bruce M., U. S. Patent 2,558,206 (June 26, 1961). (15) Barrett, E. P., and Joyner. L. G., Anal. C h a . , 23, 791-2 318, 396,330,334, 247,261,266,367,270,287,290,296,301,307, (1951). 336,338). ( 1 6 ) Barshad, Isaac, paper presented a t the 120th Meeting of the CARBON (other than charcoal). (31,35,66, 69,137, 162,247, AMERICAN CHEMICAL SOCIETY,New York. (17) Bartell, F. E.,and Dobay, Donald G., J . Am. Chem. Soc., 72, 248, 261, 263, 267, 287, 695, 330). 4388-93 (1950). SILICAGEL. (7,8, 11-14, 17, 29, 36, 66,73, 74, 76, 87, 111, (18) Beeok, O.,Cole, W. A., Ritchie, A. W., and Wheeler, A., paper 112,123,130,163,163,171,179,179,186,196,196,231,232, 236, presented a t the 119th Meeting of the AMERICAN CHEMICAL 246,250, 262,269,271,284,286, 296,S14, 320,337, 341. SOCIETY, Boston, Mass. (19) Bentley, H. R.,and Whitehead, J. K., Biochem. J . , 46, 341-5 GELSOTHERTHANSILICA. (4,8,46, 73, 76, 163, 171, 172, (1950). 186,216,232,260,262, 271,283, 284,286). (20) Berg, C. H.O., U. S. Patent 2,539,005 (Jan. 23, 1951). CLAYS. (16,32, 96,102,105,106,206,213,917,229,$SO, 276, (21) Ibid., 2,539,006 (Jan. 23, 1951). 302,315,337). (22) Ibid., 2,548.192 (April 10,1951). (23) I W . , 2,550,955(May 1, 1951). OXXDESOTHERTHAN GELS. (3,Q-12,22,38,@,66,68,68,73, (24) Berg, C. H. O., and Imhoff, Donald H., Ibid., 2,545,087 74,77,85,88,89,97,99, 100, 108, 138, 1.49, 160, 163, 173, 174, (March 13,1951). 191,197,199,213,215,219-222,2@, 2.49,26I,271,272,274,277, (25) Biebnski, A., and Tompkina, F. C., Tram. Faraday Soc., 46, 279,286, 287, 294, B98, 299, 300,SO3, 314, 322, 337). 1072-81 (1950). METALS. (6, 18,29,31,67,76,79,86,94,99,118,l24,169,183, (26) Bognar. Rezso, Nagyas Tech., 4, No. 1, 51-8 (1949). (27) Boissonnas, R.A,. HeZn. Chim. Acta, 33, 1966-7,19724,1975186-189,199,mi,,t?o7,210,211,223,269-661, 27~7,313, 316,329, 82 (1950). 339). Nature, 165, 968-9 (1950). (28) Booth, A. H., Adsorbates of Interest. NITROGEN.(9-11,82, 94, 137, 161, (29) Bosworth, R. C. L.,J . PTOC. Roy. SOC.N . 5. Wales, 83, 31-8 (1949). 163, 168, 160,173, 174,198,208,966,260,261, 271,277,311,318, (30) Boudart, Michel, paper presented a t the 120th Meeting of 344). the AMERICANCHEMICAL SOCIETY, New York. RAREGASES. (9,68,85,88,104, 120, 121, ls4, 1.43, 162,207, (31) Bowden, F. P., and Throssell, W. R.. N ~ U T S167, , 601-2 269, 281, 299, 311, 319, sa). (1951). (32) Brockmann, H.,Discussions Faraday SOC.,1949, No. 7, 68-64. WATERVAPOR(3, 26,31, 69,74,1.41,148,158,160,163,166, (33) Brockmann, H.,and Beyer, E., Angew. C h a . , Am, 133-6 166,184,209, 219-222, 230,247,948,269). (1951). HYDROCARBONS AND NONPOLAR ORGANIC VAPORS.(11,13, 18, (34) Brooks, Marvin C., and Badger, Richard M., J . Am. C h a . Soc., 90,32,36,39,41,46, 63,66,69,71,73,77,82, 90,102, 106,118, 72,4384-8 (1950). (35) Brown, Callaway. J. Phua. & CoUoid Chem., 54, 1278-81 l@,169,179,191,196,196,199,216,219,I28,231,234,24l, 949, (1950). 846,961,263, 866,970-278, 890,196,296, 319). (36) Brown, M. J , and Foster, A. G., paper presented a t the POLAR ORGANIC VAPORS.(3,11-13, 17,32,36, 36,4.2, 63,66, CHEMICAL SOCIETY, New 120th Meeting of the AMERICAN 69,66,77,87,102, 103,111, 130,1-49,176,179,206,228,881,244, York. 247,2@,261,263,267,963, $70,279,281,294,296,297,306,326, (37) Brumberg, E. M., Doklady Akad. Nauk S.S.S.R., 72, 885-8 (1950). 336,338). D. P.,and Banerjee, B., Science and Culture, 15,442-3 General Subdivisions of the Field. HEATSOF ADSORPTION (38) Burma, (1950). AND THERMODYNAMIC CONSTANTS.(1,6,9,10, II,16,18,25,60, (39) Cabrera, N., Nature, 167, 766-7 (1951). (40) Canals, E., Marignan, R., and Cordier, S., Ann. phurm. franc., 66,66,68,80-82,97,100,106, 114,123,124,131, 13.4,136, 138, 8,368-72 (1950). I 161, 162, 164, 169, 173, 174, 188, 208, 616,222, 229, 239, 249, (41) Can. Chem. Process Inda., 35, 376-7, 411 (1951). 248,253,269-261, 277,296,298,308,310,911,3@,3&f. (42) Carman, P. C., and Raal, F. A,, Nature, 167, 112-13 (1951). SURFACE AREA. (11, 13, 36, 62,61,69,87, 92, 106,116, 120, (43) Carroll, B., J . Ant. C h a . SOC.,72, 2763-4 (1950). (44) Cassidy, H. G., and Nestler, F . H. M., Discussions Faraday 191,124,138,151,163,158,163,191, 199,217,219,262, 967,269SOC.,1949, No. 7,259-64. 161,271,272,296,329,344). (45) Chem. Eng. News, 29, 3015-8 (1951). Reviews Dealing with Adsorption. (96,33, .&,64,83,97,113, (46) Ibid., p. 3017. 119,127,128,168,192,197,200,229, 233,234,256,278,293,3319 (47) Ibid., p. 3952. (48) Cleaver, C. S.,and Caasidy, H. G., J . Am. Chem. SOC.,72,1147336). 52 (1950). (49) Cockbain, E. G.,snd.McMuUen, A. I.. Tram. Faraday SOC., BIBLIOGRAPHY 47, 322-30 (1951). (50) Colburn, Allan P.,and Dodge, Barnett F., U. S. Patent 2,545.(1) Aigrain, Pierre, Dugas, Claude, and Germain, Jean, Compt. 194 (March 13, 1951). rend., 232,1100-1 (1951). (61) Constable, F.Hurn, Rev. facult.3 sci. univ. Istanbul, 15A, 127-9 (2) Amundson, N. R.,J . Phys. & Colloid Chem., 54,812-20,821-9 ft8.50). (1950). (3) Antipina, T.V.,and Frost, A. V., J . Phgs. Chem. (U.S.S.R.), (52) Corrin, M. L.,J . Phys. & Colloid Chem., 55, 612-13 (1951). 24,860-70 (1950). (53) Counsell, J. N.,Hough, L., and Wadman, W. H., Reseawh (4) Archibald, R. C.. and Eggertsen. F. T.. U. S. Patent 2.519.622 (London),4,143-4 (1951). __ (Aug. 22, 1950). (54) Craig, Lyman C., Anal. Chem.. 22, 1346-52 (1950).

stalled during World War I1 could recover ether and alcohol at a rate of 75,000,000 gallons per year a t a time when scarce dcohol was essential to the manufacture of synthetic rubber. Modern improvements in the design of solvent recovery plants utilizing activated carbon have made such equipment assume a very important place in the industrial economy of the country during peace and war.

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INDUSTRIAL AND ENGINEERING CHEMISTRY

(55) Crawford, V. A., and Tomkins, F. C., Trans. Faraday SOC.,46, 604-14 (1950). (56) Cremer, E., “Interrelationships of the Heat of Adsorption, Degree of Coverage, and Pretreatment of the Adsorbent,” paper presented a t the 120th Meeting of the AMERICAN CHEMICAL SOCIETY, New York. (57) Cremer, Erika, Wia.Cha.-Z@., 49, 1-19 (1948). (58) Cruae, K.,and Mittag, R., Z. Elektrochem., 54, 418-21 (1950). (59) Davis, S.G., Foran, M. R., Ogilvie, J. D. B., Pearce, Jesse A,, and Winkler. C. A.. Can. J . Technol.. 29. 19C-216 (1951). (60) Davydov, A. T:,and hvitskii, I. Ya., J.’Gen. Chem. (U.S.S.R.), 20, 1776-9 (1950). (61) Dean, Robert B.. J . Phys. & Colloid Chem., 55, 611-12 (1951). (62) Dean, R. B.,and Hayes, K. E., “Sorption on Monolayers. A Surface Balance for the Measurement of the Effect of Vapors on Monolayers,” paper presented a t the 119th Meeting of the AMERICAN CHEMICAL SOCIETY, Boston, Mass. (63) Dean, R. B., and Li, Fa-Si, J . Am. C h m SOC.,72, 3979-82 (1950). (64) Diebner, Leonce, Chim. anal., 33, 135 (1951). (65) Denekas, M. O.,Carlson, F. T., Moore, J. W., and Dodd, C G., IND.ENQ.CHEM.,43, 1165-9 (1951). (66) Dobay, Donald G., Fu, Ying, and Bartell, F. E., J . Am. Chem, SOC.,73, 308-19 (1951). (67) Dowden, D. A., “Chemisorption by Metals,” paper presented a t the 120th Meeting of the AMERICAN CHEMICAL SOCIETY,New York. (68) Drain, L. E., and Morrison, J. A., “Thermodynamic Propertiea of Argon Adsorbed on Titanium Dioxide from Calorimetric Measurements,” paper presented at the 120th Meeting of the AMERICAN CHEMICAL SOCIETY, New York. (69) Dubinin, M. M., and Timofeev, D. P., Dokludy Akad. Nauk S.S.S.R., 76, 555-8 (1951). (70) Dubinin, M. M., and Zaverina, E. D., Ibid., 65,295-8 (1949). (71) Dubinin, M. M., and Zaverina, E. D., J . Phys. Chem. (U.S.S.R.). 24.1262-72 (1950). (72) Durso,‘D. F.,Schall, E. D., and Whistler, Roy L., Anal. Chem., 23, 425-7 (1951). (73) Eagle, S.,and Scott, J. W., IND.ENG.CHEM.,42, 1287-94 (1950). (74)Eagleton, L. C., and Bliss, Harding, “Drying of Air in Fixed Beds,” paper presented at Am. Inst. Chem. Engrs. Meeting, Sept. 16-19, 1951,Rochester, N. Y. (75)Eischens, R. P., “The Exchange between Chemisorbed and Gaseous Carbon Monoxide on Reduced Iron,” paper presented a t the 120th Meeting of the AMERICAN CHEMICAL SoCIETT,New York. (76) Elam, Mary P., U. S. Patent 2,516,967(Aug. 1, 1950). (77) Engel, W.,and Holzapfel, L., KoEbid-Z., 119, 160-4 (1950). (78) Epstein, H. T.,J . Phys. & Coll. Chem., 54, 1053-69 (1950). (79)Erbacher, Itto, 2. Elektrochem., 54, 369-74 (1950). (80)Everett, D.H., Trans. Faraday SOC.,46, 453-9 (1950). (81)Ibid., pp. 942-57. (82) Everett, U.H., Smith, F. W., and Whitton, W. I., “Thermodynamics of Adsorption Hysteresis,” paper presented a t the 120th Meeting of the AMERICAN CHEMICAL SOCIETY,New York. (83) Farradane, J., Nature, 167, 120 (1951). (84) Ferguusson, R. R., and Barrer, R. M., Trans. Faraday SOC.,46, 400-7 (1950). (85) Forestier, Hubert, and Kiehl, J. P., Compt. rend., 230, 2288-90 (1950). (86) Forestier, Hubert, and Maurer, J., Ibid., 232, 1664-6 (1951). (87)Foster, A. Graham, J . Phys. & Colloid Chem., 55, 638-43 (1951). (88) Frederikse, H. P. R., and Gorter, C. J., Physica, 16, 402-18 (1950). (89) Fricke, R.,and Neugebauer, W., Naturwissenschuften, 37, 427 (1950). (90) Friz, Hans, Z.Elektrochem., 54, 538-40 (1950). (91) Frumkin, A. N.,DokZudy Akad. Nauk S.S.S.R., 69? 8214 (1949). (92) Fu,Ying, and Bartell, F. E., J . Phys. & Colloid Chem., 55,66275 (1951). (93) Fucik, K.,and Prochazka, Z., Chem. L i s f y , 44, 165 (1950). (94) Fumiwara, Shizuo, Bull. Chem. SOC.Japan, 23, 20-2 (1950). (95) Gapon, E. N., and Zhupakhina, E. S., Doklady Akad. Nauk S.S.S.R., 72,721-4 (1950). (96) Garcia, F. G., Anales fis. y quint. (Madrid), 45B. 1183-1210 (1949). (97) Garner, W.E.,Stone, F. S. and Tiley, P. F., “Heats of Adsorp tion on Oxides,” paper presented a t the 119th Meeting of the AMERICAN CHEMICAL SOCIETY,Boston, Mass. (98) Gault, Henry, and Ronez, Christiane, Bull. SOC. chim. France, 1950,597-8.

Val. 44, No. 1

(99) Ghosh, J. C., Sastri, M. V. C., and Kid,E. A., Research, 3,6&4 (1950). (100) Ghosh, J. C., Sastri, M. V. C., and Vedaraman, Currmt sei. (India), 19,342 (1950). (101) Gilson, A. R., Chemistry 61. Industry, 1951, 185. (102) Glaeser, R., C m p l . rend., 232, 1496-8 (1951). (103) Glueckauf, E.,J. Am. Chem. SOC.,73,849-50 (1951). (104) Glueckauf, E.,J. Chem. SOC.,1949, 3280-5. (105) Gonzales, Juan de D. Lopez, and Deitz, V. R.. “Surface Area Changes in an Original and Activated Bentonite,” paper psented a t the 119th Meeting of the AMERICANCHEMICAL 80CIETY,Boston, Maw. (106) Granquist, W.T.,IND. ENG.CHEM.,42,2572-5 (1950). (107) Grant, R. A., and Stitich, 5. R., Chemistry & Indwtry, 1951, 230. (108) Grasshof, H., Angew. Chem.,63,96-7 (1951). (109)Gregg, S. J., and Sing, K. 5. W., J . Phys. & Colloid Chem., 55, 592-7 (1951). (110) Gunthard, H. H.,Kohler, M., Xster, H. R,,Auerswald, H., and Messikommer, B., Helv. Chim. Acta, 33, 1118-26 (1950). (111) Gyani, B. P.,J . Indian Chem. SOC.,27,577-85 (1950). (112) Gyani, B.P., J . Indian C h . Soc., Ind. & News Ed., 13, No. 1, 1-7 (1950). (113) Hais, I. M., Chem. Listy, 42, 125-37 (1948). (114) Halsey, G. D.,“Entropy Effects in Multilayer Adsorption,” paper presented a t the 120th Meeting of the AMERICAN CHEMICAL SOCIETY, New York. (115) Halsey, G. D., J. Am. C h a . SOC.,73,2693-6 (1951). (116) Halsey, G. D.,J . Phys. & Colloid Chem., 55, 21-6 (1951). (117) Harasawa, Shiro, J . C h . SOC.Japan, 71, 636-9 (1950). (118) Harkins, W.D., and Loeser, E. H., J . C h a . Phys., 18, 556-60 (1950). (119) Harris, B. L.,IND.ENQ.CHEM.,43, 46-55 (1951). (120) Harris, B. L.. and Wolock, I., Ojfficial Digest Fedmation Paint & Varnish Production Clubs (September 1950). (121) Ibid. (October 1950). (122) Harris, J. 0 , Chemirltry & Industry, 1951,255. (123) Harteck, Paul, and Melkonian, G. A.. Natunuissemchaften, 37, 450 (1950). (124) Healy, F. H., Chessick, J. J., and Zettlemoyer, A. C., “Adsorg tion of Gases on Metals,” paper presented a t the 119th Meet. CHEMICAL SOCIETY, Cbveland, Ohio. ing of the AMERICAN (125) Heijke, H.B. van der, and Aten, A. H. W., Jr., J . Phys. & Colloid Chem., 55, 740-4 (1951). (126) Herbo, C., Lefebvre, C., and Muylle, R., Ind. chim. belge, 16, 82-5 (1951). (127) Hesse, Gerhard, Chem.-Ztg., 74, 634-6, 647-9 (1950). (128) Higuchi, Izumi, C h . Researches (Japan), 9,85-131 (English summary, 132) (1951). (129) Higuchi, Izumi, J. Chem. SOC.Japan, 71, 14205 (1950). (130) Higuchi, Izumi, Science Rep&. TBhoku Univ., 33. 174-81 (1950). (131) Hill, Terrell L.,J. Chem. Phys., 18,791-6 (1950). (132)Ibid., 19, 261-2 (1951). (133) Hill, Terrell L., paper presented a t the 120th Meeting of the AMERICAN CHEMICAL SOCIETY,New York. (134) Hill, T. L., J. Chem. Phys., 18,246-56 (1950). (135) Hill, T. L.,J. Phys. & Colloid Chem., 54, 1186-91 (1960). (136) Hill, Terrell L.,Jura, George, and Kemball, Charles, paper presented at the 120th Meeting of the AMERICAN CHEMICAL SOCIETY, New York. (137) Hill, T. L.,Emmett, P. H., and Joyner, L. G.. paper presented a t the 119th Meeting of the AMERICAN CHEMICAL SOCIETY, Boston, Mass. (138) Hirst, W., and Lancaster, J. X., Research, 3, 336-7 (1950). (139) Hirtz. J., and Bernard, R., J. chim. phus.. 48. 52-4 (1951). (140) Holman, Ralph T., and Hagdahl, &nnart, Anal. Chen., 23, 794-7 (1951). (141) Hoover, S.R., and Mellon, E. F., J . Am. Chem. Sor.. 72,2562-6 (1950). (142) Hopkins, R. L.,IND. ENG.CHEW,43, 1456-8 (1951) (143) Hough, E.W., Wood, B. B., Jr., and Raaea, M. J., paper presented a t the 119th Meeting of the AMERICAN CHEMICAL SoCIETY,Cleveland, Ohio. (144) Howard, 0.A,, and Martin, A. J. P., Biochem. J . , 46, 532-8 (1950). (145)Hutchinson, E.,paper presented at the 120th Meeting of the AMERICAN CHEMICAL SOCIETY, New York. (146)Huttig, G. F., and Theimer, O., Kolloid-Z., 119, 69-73 (1950). (141) Huttig, G. F.. and Theimer, 0 , paper presented at the 120th Meeting of the AMERICAN CHEMICAL SOCIETY, New Yo1 k. (148) Huttig, G. F.,Theimer, O., and Mehlo, W. KoZEoid-Z., 121,4 (1951). (149) Iida, Takeo, and Ishimoto, Kenso, J . Pharm. SOC.Japan, 64, 303-4 (1944).

January 1952

INDUSTRIAL AND ENGINEERING CHEMISTRY

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